stm32l4xx_hal_dac.c File Reference

DAC HAL module driver. This file provides firmware functions to manage the following functionalities of the Digital to Analog Converter (DAC) peripheral: + Initialization and de-initialization functions + IO operation functions + Peripheral Control functions + Peripheral State and Errors functions. More...

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Detailed Description

DAC HAL module driver. This file provides firmware functions to manage the following functionalities of the Digital to Analog Converter (DAC) peripheral: + Initialization and de-initialization functions + IO operation functions + Peripheral Control functions + Peripheral State and Errors functions.

Author:

MCD Application Team

Version:

V1.1.0

Date:

16-September-2015

  ==============================================================================
                      ##### DAC Peripheral features #####
  ==============================================================================
    [..]        
      *** DAC Channels ***
      ====================  
    [..]  
    STM32L4 devices integrate two 12-bit Digital Analog Converters

    The 2 converters (i.e. channel1 & channel2)
    can be used independently or simultaneously (dual mode):
      (#) DAC channel1 with DAC_OUT1 (PA4) as output or connected to on-chip 
          peripherals (ex. OPAMPs, comparators).
      (#) DAC channel2 with DAC_OUT2 (PA5) as output or connected to on-chip 
          peripherals (ex. OPAMPs, comparators).
      
      *** DAC Triggers ***
      ====================
    [..]
    Digital to Analog conversion can be non-triggered using DAC_TRIGGER_NONE
    and DAC_OUT1/DAC_OUT2 is available once writing to DHRx register. 
    [..] 
    Digital to Analog conversion can be triggered by:
      (#) External event: EXTI Line 9 (any GPIOx_PIN_9) using DAC_TRIGGER_EXT_IT9.
          The used pin (GPIOx_PIN_9) must be configured in input mode.
  
      (#) Timers TRGO: TIM2, TIM3, TIM4, TIM5, TIM6 and TIM7 
          (DAC_TRIGGER_T2_TRGO, DAC_TRIGGER_T3_TRGO...)
  
      (#) Software using DAC_TRIGGER_SOFTWARE
  
      *** DAC Buffer mode feature ***
      =============================== 
      [..] 
      Each DAC channel integrates an output buffer that can be used to 
      reduce the output impedance, and to drive external loads directly
      without having to add an external operational amplifier.
      To enable, the output buffer use  
      sConfig.DAC_OutputBuffer = DAC_OUTPUTBUFFER_ENABLE;
      [..]           
      (@) Refer to the device datasheet for more details about output 
          impedance value with and without output buffer.

      *** DAC connect feature ***
      =============================== 
      [..] 
      Each DAC channel can be connected internally. 
      To connect, use
      sConfig.DAC_ConnectOnChipPeripheral = DAC_CHIPCONNECT_ENABLE;
                                               
      *** GPIO configurations guidelines ***
      =====================
      [..] 
      When a DAC channel is used (ex channel1 on PA4) and the other is not 
      (ex channel2 on PA5 is configured in Analog and disabled).
      Channel1 may disturb channel2 as coupling effect.
      Note that there is no coupling on channel2 as soon as channel2 is turned on.
      Coupling on adjacent channel could be avoided as follows:
      when unused PA5 is configured as INPUT PULL-UP or DOWN. 
      PA5 is configured in ANALOG just before it is turned on.     
                                               
      *** DAC Sample and Hold feature ***
      ========================
      [..] 
      For each converter, 2 modes are supported: normal mode and 
      "sample and hold" mode (i.e. low power mode).
      In the sample and hold mode, the DAC core converts data, then holds the 
      converted voltage on a capacitor. When not converting, the DAC cores and 
      buffer are completely turned off between samples and the DAC output is 
      tri-stated, therefore  reducing the overall power consumption. A new 
      stabilization period is needed before each new conversion.

      The sample and hold allow setting internal or external voltage @
      low power consumption cost (output value can be at any given rate either 
      by CPU or DMA).

      The Sample and hold block and registers uses either LSI & run in 
      several power modes: run mode, sleep mode, low power run, low power sleep 
      mode & stop1 mode.
          
      Low power stop1 mode allows only static conversion.
          
      To enable Sample and Hold mode 
      Enable LSI using HAL_RCC_OscConfig with RCC_OSCILLATORTYPE_LSI &
      RCC_LSI_ON parameters.

      Use DAC_InitStructure.DAC_SampleAndHold = DAC_SAMPLEANDHOLD_ENABLE;
         & DAC_ChannelConfTypeDef.DAC_SampleAndHoldConfig.DAC_SampleTime,
           DAC_HoldTime & DAC_RefreshTime;
    


       *** DAC calibration feature ***
       =================================== 
      [..] 
       (#)  The 2 converters (channel1 & channel2) provide calibration capabilities.  
       (++) Calibration aims at correcting some offset of output buffer.
       (++) The DAC uses either factory calibration settings OR user defined 
           calibration (trimming) settings (i.e. trimming mode).
       (++) The user defined settings can be figured out using self calibration 
           handled by HAL_DACEx_SelfCalibrate.
       (++) HAL_DACEx_SelfCalibrate:
       (+++) Runs automatically the calibration.
       (+++) Enables the user trimming mode
       (+++) Updates a structure with trimming values with fresh calibration 
            results. 
            The user may store the calibration results for larger 
            (ex monitoring the trimming as a function of temperature 
            for instance)

       *** DAC wave generation feature ***
       =================================== 
       [..]     
       Both DAC channels can be used to generate
         (#) Noise wave 
         (#) Triangle wave
            
       *** DAC data format ***
       =======================
       [..]   
       The DAC data format can be:
         (#) 8-bit right alignment using DAC_ALIGN_8B_R
         (#) 12-bit left alignment using DAC_ALIGN_12B_L
         (#) 12-bit right alignment using DAC_ALIGN_12B_R
  
       *** DAC data value to voltage correspondence ***  
       ================================================ 
       [..] 
       The analog output voltage on each DAC channel pin is determined
       by the following equation:
       [..]
       DAC_OUTx = VREF+ * DOR / 4095
       (+) with  DOR is the Data Output Register
       [..]
          VEF+ is the input voltage reference (refer to the device datasheet)
       [..]
        e.g. To set DAC_OUT1 to 0.7V, use
       (+) Assuming that VREF+ = 3.3V, DAC_OUT1 = (3.3 * 868) / 4095 = 0.7V
  
       *** DMA requests ***
       =====================
       [..]
       A DMA1 request can be generated when an external trigger (but not a software trigger) 
       occurs if DMA1 requests are enabled using HAL_DAC_Start_DMA(). 
       DMA requests are mapped as following:          
      (#) DAC channel1: mapped either on
      (++) DMA1 request 6 channel3 
      (++) or DMA2 request channel4 which must be already configured
      (#) DAC channel2: mapped either on
      (++) DMA1 request 5 channel4 
      (++) or DMA2 request 3 channel5 which must be already configured 
     [..]
    (@) For Dual mode and specific signal (Triangle and noise) generation please 
        refer to Extended Features Driver description        
      
                      ##### How to use this driver #####
  ==============================================================================
    [..]          
      (+) DAC APB clock must be enabled to get write access to DAC
          registers using HAL_DAC_Init()
      (+) Configure DAC_OUTx (DAC_OUT1: PA4, DAC_OUT2: PA5) in analog mode.
      (+) Configure the DAC channel using HAL_DAC_ConfigChannel() function.
      (+) Enable the DAC channel using HAL_DAC_Start() or HAL_DAC_Start_DMA() functions.

     *** Calibration mode IO operation ***
     ======================================
     [..]    
       (+) Retrieve the factory trimming (calibration settings) using HAL_DACEx_GetTrimOffset()
       (+) Run the calibration using HAL_DACEx_SelfCalibrate() 
       (+) Update the trimming while DAC running using HAL_DACEx_SetUserTrimming()

     *** Polling mode IO operation ***
     =================================
     [..]    
       (+) Start the DAC peripheral using HAL_DAC_Start() 
       (+) To read the DAC last data output value, use the HAL_DAC_GetValue() function.
       (+) Stop the DAC peripheral using HAL_DAC_Stop()
       
     *** DMA mode IO operation ***    
     ==============================
     [..]    
       (+) Start the DAC peripheral using HAL_DAC_Start_DMA(), at this stage the user specify the length 
           of data to be transferred at each end of conversion
       (+) At the middle of data transfer HAL_DAC_ConvHalfCpltCallbackCh1() or HAL_DACEx_ConvHalfCpltCallbackCh2()  
           function is executed and user can add his own code by customization of function pointer 
           HAL_DAC_ConvHalfCpltCallbackCh1() or HAL_DACEx_ConvHalfCpltCallbackCh2()
       (+) At The end of data transfer HAL_DAC_ConvCpltCallbackCh1() or HAL_DACEx_ConvHalfCpltCallbackCh2()  
           function is executed and user can add his own code by customization of function pointer 
           HAL_DAC_ConvCpltCallbackCh1() or HAL_DACEx_ConvHalfCpltCallbackCh2()
       (+) In case of transfer Error, HAL_DAC_ErrorCallbackCh1() function is executed and user can 
            add his own code by customization of function pointer HAL_DAC_ErrorCallbackCh1
       (+) In case of DMA underrun, DAC interruption triggers and execute internal function HAL_DAC_IRQHandler.
           HAL_DAC_DMAUnderrunCallbackCh1() or HAL_DACEx_DMAUnderrunCallbackCh2()  
           function is executed and user can add his own code by customization of function pointer 
           HAL_DAC_DMAUnderrunCallbackCh1() or HAL_DACEx_DMAUnderrunCallbackCh2() and
           add his own code by customization of function pointer HAL_DAC_ErrorCallbackCh1()
       (+) Stop the DAC peripheral using HAL_DAC_Stop_DMA()
                    
     *** DAC HAL driver macros list ***
     ============================================= 
     [..]
       Below the list of most used macros in DAC HAL driver.
       
      (+) __HAL_DAC_ENABLE : Enable the DAC peripheral
      (+) __HAL_DAC_DISABLE : Disable the DAC peripheral
      (+) __HAL_DAC_CLEAR_FLAG: Clear the DAC's pending flags
      (+) __HAL_DAC_GET_FLAG: Get the selected DAC's flag status
      
     [..]
      (@) You can refer to the DAC HAL driver header file for more useful macros  
   
 

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Definition in file stm32l4xx_hal_dac.c.